An analog type audio signal transmission scheme is mainly used to transmit audio signals. According to the analog type audio signal transmission scheme, a transmission signal is generated by modulating the frequency of infrared rays using an analog audio signal and the transmission signal is spatially transmitted. For instance, such an analog type audio signal transmission scheme can be employed to transmit audio signals between a CD player and a speaker.
However, since the analog type audio signal transmission scheme requires modulation of the frequency of the infrared rays using an analog audio signal, sound quality may be degraded during signal transmission.
In addition, according to the analog type audio signal transmission scheme, it may be difficult to add a digital type control signal, which is used to adjust sound quality between the analog type audio signal and audio equipment, to the transmission signal, so the control signal must be transmitted separately from the audio signal.
To solve the above problem, an audio signal transmitting apparatus has been developed to optically transmit digital type audio signals, which are rarely degraded in the transmission path, and studies and research have been actively conducted to effectively transmit audio signals without degrading the sound quality of the audio signals.
Meanwhile, studies and research have been further conducted to transmit the audio signal to a recipient by adding specific data to the audio signal. However, there are various problems in that the audio signal may be distorted as the data are added to the audio signal and it may be difficult to effectively add the data to the audio signal and to detect the added data at the recipient, so such a data addition scheme represents a limitation in realizing the acoustic communication in an audio frequency band. Accordingly, technologies capable of solving the above problems are required.